3.3.1 Non-interactive mode

To make mixvm work in non-interactive mode, use the -r
flag. Thus, to run our hello.mix program, simply type

mixvm -r hello RET

at your command prompt, and you will get the following output:

MIXAL HELLO WORLD

Since our hello world program uses MIX’s device number 19 as
its output device (see Writing a source file), the output is
redirected to the shell’s standard output. Had you used any other MIX
output devices (disks, drums, line printer, etc.), mixvm would
have created a file named after the device used (e.g. disk4.dev)
and written its output there12.

The virtual machine can also report the execution time of the program,
according to the (virtual) time spent in each of the binary instructions
(see Execution times). Printing of execution time statistics is
activated with the -t flag; running

mixvm -t -r hello RET

produces the following output:

MIXAL HELLO WORLD
** Execution time: 11

Sometimes, you will prefer to store the results of your program in MIX
registers rather than writing them to a device. In such cases,
mixvm’s -d flag is your friend: it makes mixvm to
dump the contents of its registers and flags after executing the loaded
program. For instance, typing the following command at your shell’s
prompt

which, in addition to the program’s outputs and execution
time, gives you the contents of the MIX registers and the values of the
overflow toggle and comparison flag (admittedly, rather uninteresting in
our sample).

As you can see, running programs non-interactively has many
limitations. You cannot peek the virtual machine’s memory contents, not
to mention stepping through your program’s instructions or setting
breakpoints13. Enter interactive mode.